This invention relates to automatic meter readers, particularly automated chart recorders.
Chart recorders sense physical parameters, such as fluid flow, volumes, pressure and temperature, and are often used in oil and gas producing, processing, and transportation facilities. These chart recorders consist of sensing elements mechanically linked to actuate pens that mark on a chart. The chart rotates or is otherwise advanced by a chart drive. The pens travel across the chart, marking the variables on the advancing chart paper.
Past attempts to capture the sensed variables at the chart recorders have included linkage driven linear or rotational displacement elements as for example the proposal found in U.S. Pat. No. 4,414,634 issued Nov. 8, 1983. This method requires moving parts such as linkage connections that are subject to wear. These devices require unique calibrations from those normally performed on the chart recorder.
Other attempts have included the use of a camera and supporting hardware mounted in front of the chart to record and disseminate the chart values as disclosed in U.S. Pat. No. 4,837,708 issued Jun. 6, 1989. Size, complexity, cost, potential for tampering or theft and reliability would have hampered the adoption of this method.
A chart digitizing system pioneered by the patent applicant has been developed using existing pen position determining art, and proprietary software to enable the manual tracing of the chart lines once the chart has been created, taken off and placed on the digitizing tablet.
Conventional chart recorders suffer disadvantages in that there is an inherent delay in the getting the information from the chart and into the system. The chart typically has to be completed, taken off, interpreted before getting the results. The delay presents challenges and difficulties in optimizing operations needing the data.
The invention differs substantially in that the invention allows the pen positions to be detecteted and logged at the recording or indicating instrument in real time.
There is therefore provided in accordance with an aspect of the invention an automatic meter reader, comprising a meter having a movable arm, the movable arm having an indicator tip, the indicator tip being movable through a range of positions in response to the meter sensing a physical parameter, and a digitizer mounted on the meter, the digitizer having a digitizing grid positioned adjacent the indicator tip for sensing the position of the indicator tip.
The use of the invention allows the chart recorder pen positions to be detected and processed as the chart is being created. The digital data can be stored to memory and communicated to other devices. The information is then readily available for use through a variety of common interfaces.
Equipping the marking devices so their position can be detected at the point of contact on the chart or chart backing surface allows a direct correlation between the chart recorded data and the logged values without special calibration efforts on the recorder.
This system has the advantage of operating as a dual system where the ink on paper chart can be retained as the pen functions are logged.
The system has the further advantage that the position sensing grid and electronics has no moving parts to wear. The system will be accurate, reliable, be easy to produce and install.
These and other aspects of the invention are described in the detailed description of the invention and claimed in the claims that follow.